Re: Why the planes did not crumple

On 11 Jun 2006 02:26:39 -0700, u2r2h@xxxxxxx wrote:

structure. At that speed, however (and as laid out in my first post),
they went right through the building outer structure.

Sitll, would the wing-tips or even the tail wings not bounce off?

The wing tips? Probably not. The front spar runs all the way to the
end of the wings. I'm not sure what you mean by "tail wings". If you
mean the horizontal stabilizors, no. They would pass through the
large holes already created by the wings and fuselage. If you mean
the vertical stabilizor, I knew that question was coming so I started
looking into it. It turns out that the vertical stabilizor on a
commercial jet is structurally very similar to a wing. NORMALLY, it
doesn't carry much side load, but it is a symmetrical airfoil that is
designed to carry large loads if the aircraft every starts to spin. If
the aircraft enters a spin, that massive vertical stabilizor needs to
couteract the rotation of the entire airframe. So there is a very
significant front spar.

However, there is nowhere near the mass in the vertical stabilizor as
there is in the wings (which are full of fuel) and the engines are no
longer pushing the airframe into the building. The impact force here
is pure momentum.

So, how does this lighter (although still beefy with a significant
leading edge spar) structure penetrate the building?

Well, the forward fuselage hit the building about .3 seconds before
the tail and the wings hit about .15 seconds before the tail. There
is already massive structural damage just below where the tail hits
and the explosion of the 150,000+ pounds of jet fuel has already
started. The tail is hitting massively weakened structure to begin
with.

Now, I doubt this does the entire trick if not for one more very
significant point: The tail is more or less vertical when it hits.
The major structure of the building is designed to carry vertical
loads and we have, in essence, hit a single load carrying piece of
structure that is free at the bottom.

A buddy of mine (who is a Civil engineer) explained it like this: Take
one of those doors that has the vertical strands of beads that hang in
front of the door. Pretend is is nice and wide. Run at it full speed
with your arms outstretched. It is pretty hard to push your way
through all of the beads, but you can if you run fast enough. Now, get
on a skateboard and hit the same door hanging at the same speed but
sideways, Even though you still hit some of the strands, you pass
through with almost no resistance.

That is essentially what the tail saw. The forward fuselage and wing
structure had already passed through the shell of the building
weakening it (the structure is now supported only from the top). When
the tail its, it hits only a very few heavily damaged supporting
members and passes through.

Now, all of this being said, I am not saying that everything out to
the very end of the wing and very top of the tail passes through the
wall. It probably doesn't . There are some anticollision lights,
antennae, and other light items out at the ends. However, they are a
very small part of the aircraft and would not "bounce off" the
building. They tend to be oblitterated in a cloud of debris. We
rarely find them intact after a high speed impact. The best we find
are tiny pieces if we can identify them at all.

So, to answer your basic question, the vast majority of the aircraft
passes through the shell of the wall, but doesn't have enough energy
left over to exit the other side. What doesn't pass through is a very
small portion of the total aircraft (probably less than .1% by wieght)
and is destroyed in the impact.


fine, but would it also destroy the BlackBoxes?

In this case, I highly doubt the boxes survived intact. If they could
find them in the rubble, however, I believe that getting data out of
them is possible.

Some reports say they were found. In any case we people are
not allowed to know.

I have heard reports both ways. As you know, the contents of the CVR
are never released, although information off the FDR is often
released. I know that they were looking very hard for the boxes, but
I don't know what was ever found.

However, look at the aircraft that crashed in Pennsylvania. They
never did release the entire CVR transcript. This is SOP for the
NTSB. As an engineer, I'd love to hear all of these, but I understand
their reasons.

Still, I'm with you and would like to know if they every found the
boxes and /or got anything useful out of them.




Then the INCREDIBLE collapse!! The second-hit tower EXPLODED first!
.. and they neatly came down ... the massive steel core did not keep
standing
up even though it was anchored in the bedrock and had very high
vertical strength.

To be honest with you, this was what I had the hardest time with as

Can you address why the vertical center core columns vanished?

Well, they didn't really vanish, the simply collapsed with the rest of
the building. As the upper levels pancake down on top of each other
and the entire top section drops, it collapses the central core just
like it collapses the outer shell. The building was designed such
that the outer shell and central core carried about equal amounts of
the building load. You see in the videos of the collapse that the
outer shell steel is breaking like popsicle sticks. The central core
would be the same.


I fully expected the upper structure to
"topple" onto nearby buildings and take out half of Manhattan.

me too.

http://www.propagandamatrix.com/collapse.html
shows a nice photo of the top-section leaning over...

Yeah. They got really lucky. As you watch the video, you can clearly
see that one side of the shell holds longer than the other side. The
core has given way and one side of the shell has given way. The only
thing that prevents that top section from tipping all the way over is
that as the front (down) corner of the intact upper section starts to
encounter intact structure below it, it slows. By this time, the back
part of the shell has failed and has started to drop. If you watch
closely, you can see the tipping motion stop and perhaps even start to
come back a little as it disappears into the dust cloud.

Had that back structure held just a little longer, that would have
been a whol lot uglier!


stresses around both the core and the shell causing the remaining
structure to start buckling towards the floor slabs (the core
structure buckled out, the walls in). When the first section finally
buckled, the whole thing collapsed vertically as the lower floors
couldn't hold the load of the upper floors coming down on top of them.

the pancake theory. Which sound believable, especially when watching
the footage of the collapses.

There was a very good 2 hour show on the forensics of the collapse
that I caught awhile back. After you knew what to look for, it was
easy to pick out some of the sections of interest.


One thing to remember is that modern buildings are DESIGNED to be
taken down by implosion. They are DESIGNED to collapse vertically
like this.

The world-trade center was designed for demolition by explosives?

Not neccessarily by explosives, but yes, when they put these buildings
up, they have to consider that they might need to come down some day.

Remember that this wasn't the first time they tried to bring down
these towers. The first time was with a van loaded with explosives
that was supposed to be parked right next to one of the major corner
supports. Fortunately, the idiot driving the van couldn't find a
parking place in the right area so he parked elsewhere (instead of
just double parking and running!). As you may recall, these were the
same geniuses who later tried to claim insurance on the rented van
claiming it was stolen!


Was the energy from the top-floors coming down sufficient for the
pulverization of concrete into the finest dust?
http://911research.wtc7.net/wtc/evidence/dust.html

Quite definitely.

Others have said that the fine-ness of the particles cannot be
achieved just by crushing.

Measurements: http://delta.ucdavis.edu/WTC.htm

It is hard to create concrete particles by crushing, but it can be
done. Regardless, crushing is probably not what created most of the
particles, Concrete is very strong in compression, but very weak in
tension. That is why you put rebar in concrete structure. However,
once you manage to "bend" a concrete slab, you put a large portion of
it in tension. It breaks apart fairly easily at that point. As the
building collapsed, the floor sections were constantly going in and
out of tension and compression creating your fine dust.

Remember, the vast majority of the material in the building collapsed
down into the rubble heap. The WTC extended many stories below ground
and the collapse did NOT end at ground level. The cloud of dust was a
very small portion of the entire mass of the buildings. You didn't
pulverize all of the concrete. Even pulverizing .5% of the concrete
would have created a dust cloud far bigger than was actually seen. Not
that the UC Davis study in the link above notes that a significant
percentage of the dust was from wall materials (interior), crushed
computer equipment, plastics, glass, etc. all of which is much weaker
(and easier to crush) than concrete.


Could the trajectory of the rubble be achieved with just the
air-pressue?
http://www.saunalahti.fi/wtc2001/soldier5.htm

I think that most of the debris was probably
thrown away from the scene on ballistic trajectories generated by the
force of the collpase (the same forces that crumpled the steel and
pulverized the concrete).

What I meant was the spread of the explosion plumes.

But there are many other indications that the collapse of the
WTC was not due to the pancake theory.

http://911research.wtc7.net/materials/contrib/911_physics_v9a.htm

http://www.911hoax.com/Morgan_Reynolds_911_Hoax.html

Interesting sites. This is turning into another Grassy Knoll
conspiracy theory.

Both sites make a very fundamental error at the beginning. The WTC
construction as fundamentally different from nearly every other
building in the world. In my original response, I very openly state
that most structural experts agree that IF the WTC had been made with
normal contsruction techniques, it would not have collapsed. Both
sites assume that the core was the major load bearing part of the
building. This is incorrect. The core and the shell carried
approximately equal amounts of the structural load of the building.
There was no internal truss structure. Also note that the shell and
the core were NOT mutually freestanding. They REQUIRED the stiffness
of the floor sections joining the two to in order to stand to any
great height.

The pancake theory isn't quite correct. Only a couple of floors
collapsed in this way. When the concrete slabs collapsed, they pulled
the walls in and the core out. This dropped the top part of the
buildings onto the intact lower part and the rest was crushed.

As for all the BS about how steel behaves, this guy has no clue what
he's talking about. Steel is about the most complex material there is
and creating certain steels requires a complex heating and cooling
sequence (with multiple heatings and coolings) to get the correct
molecular structure. While steel DOES conduct energy quite well, the
key to the collpase were some small clips that were largely bounded by
a very good insulator - concrete. The clips were fairly small and
they were found in the annealed condition after the colapse. They
were exposed to high heat and the did lose the majority of their
strength. They were also nearly flat.

The metal structure in the areas of concern tell the story. They were
exposed to high heat and they did ductilely deform.

Actually, the best picture in both the websites (and they do have a
lot of fact correct, it is how they try to link them together that
causes their arguments to fall apart) is the chimney being broght down
at the end of the first website. All I can say is "Bingo!" That is
exactly what happened. The only difference is that instead of
explosives, you used aircraft and fire to bring the buildings down.
The rest of the collapse was exactly like an implosion.


I've found aircraft wreckage in amazing
places after high speed impacts. I don't have a map of where

http://www.physics911.ca/ has a collection..

Why is it always the Canadians who come up with all of the good stuff?

I've barely touched the surface, but there is lots of good stuff here.
I didn't find a detailed map of the debris, but in the areas I did
look, I didn't find anything horribly surprising. The major
structural pieces seemed to stay pretty close. Some of the lighter
cladding traveled a ways down some side streets, but that isn't
horribly surprising. There was dust over a wide area, but again, that
isn't terribly surprising.

Is there something specific you'd like to point out? If I can't
explain it, I'll admit it.


One absolutely key thing to remember when reading the websites you've
been searching out. If it was really bombs that caused the building
collapse, why are all of the structure in the collapse initiation zone
buckled towards the CENTER of the floor area and why is it all ductile
flow of annealed metal? A bomb creates forces AWAY from the point
where it explodes and the metal in the are fails in tensile overload.


Have you seen the WHATS THE TRUTH video?
http://www.911podcasts.com/display.php?vid=95

it shows some footage that I think will change your mind

Now that is a monster video. I'm not used to having to wait to view
things anymore (the last video this large I grabbed was a hydrogen
cloud collapse into stars (here if you care, the half gig version is
the best http://www.ukaff.ac.uk/starcluster/)).

80% and still waiting...already answered the thermite portion...

99%...Yipee!

Well, all I can say it is a darn good thing I don't investigate
aircraft crashes the way this video analyzes the collapses. They pick
and choose what facts to present without analyzing the entire event.

Nothing in here changes my mind. In fact, many of the facts don't
even support the argument that the video is trying to present.

BTW, most of the structural engineers I know aren't at all surprised
that WTC7 came down. They were more surpirsed that the others did
not. WTC7 shared a common foundation with the other large buildings.
When the first two came down, it damaged the foundations of all of the
other "deep foundation" buildings (including WTC7).

I completely fail to understand why everybody is so surprised at how
these buildings came straight down. THEY ARE DESIGNED TO COME DOWN
THIS WAY! Find any picture of building collapses after earthquakes.
You'll find that the buildings don't tip over, they come straight
down.

Did it surprise me that they didn't immediately tip over? Yep. Did
it surprise any of the Civil Engineers I know? Nope. And after it
was explained to me, it didn't suprise me any more either.


I guess my point is that the bomb theory doesn't fit the story that
the metal tells.

You have heard about the rusty steel in the hands of
Prof Steven Jones .. evidence of thermite being used?

Nope, I haven't heard of this. Rusty steel doesn't surprise me and
thermite is made of:

1. Aluminum.
2. Hematite
3. Magnetite

I'd love to hear what his evidence of thermite being used. I hope it
is more than he found these metals at the scene. The WTC was rotten
with all 3 of them. Oh, and your typical building starts to corrode
before it is even complete! There should have been rusy steel beams
all over the place.

And do you have any concept about the amount of Thermite you'd need to
bring down the WTC? First, you'd need acess to the major structure
(read, tear out walls) over probably 1-2 floors (around the ENTIRE
floor). Next you'd need to get a HECK of a lot of Thermite into the
buildings and wire it and detonate it all without anybody noticing!

It would take you months just to get all the explosives into place!
.

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